Automatic power transmissions are currently in wide spread use in passenger vehicles and trucks. As is well known, the automatic transmission provides a plurality of speed ratios in both the forward direction and at least one reverse speed ratio. The speed ratios are established through the use of a plurality of planetary gearsets. The engagement of the gearsets is controlled by a number of fluid-operated torque-transmitting mechanisms, commonly termed clutches and brakes.
It has become a standard to provide at least four forward speed ratios in automatic transmissions for use in passenger vehicles. More recently, automobile manufacturers have increased the forward speed ratios to six and in some instances seven or eight. This, of course, requires the addition of planetary gearsets. However, it is desirable to minimize the number of torque-transmitting mechanisms to reduce cost and overall size of the transmission.
A number of the currently proposed eight speed planetary transmissions provide three planetary gearsets and five torque-transmitting mechanisms. One problem facing transmission designers and manufacturers is the packaging of the planetary gearsets and the torque-transmitting mechanisms. It is preferable to arrange the gearsets and torque-transmitting mechanisms in a way that minimizes the overall size of the transmission as well as reduces manufacturing complexity.
Thus, there is a need for a new and improved multi-speed transmission. The arrangement of the gearsets and the torque-transmitting mechanisms of the transmission should minimize the size and manufacturing complexity of the transmission.